Loans and ACL - Allowance for Credit Losses (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance				$ 4,857
Provision for credit losses		$ 488	$ 451	946	$ 951
Ending balance		4,899		4,899
Commercial: | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,307	1,360	1,284	1,404
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(120)	(83)	(222)	(180)
Recoveries		31	14	55	46
Provision for credit losses		96	46	196	68
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	(5)	1	(4)	0
Ending balance		1,309	1,338	1,309	1,338
Commercial: | CRE
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		604	663	643	616
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(38)	(97)	(108)	(200)
Recoveries		3	5	10	12
Provision for credit losses		(6)	90	18	233
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		563	661	563	661
Commercial: | Commercial construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		280	198	257	174
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		0	0	0	0
Recoveries		1	1	1	1
Provision for credit losses		(22)	7	1	31
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		259	206	259	206
Consumer: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		227	222	204	298
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(1)	(1)	(2)	(2)
Recoveries		0	2	2	3
Provision for credit losses		(6)	(18)	16	(94)
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		220	205	220	205
Consumer: | Home equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		93	90	89	89
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(4)	(3)	(6)	(6)
Recoveries		4	4	8	9
Provision for credit losses		(1)	(3)	1	(4)
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		92	88	92	88
Consumer: | Indirect auto
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		955	923	955	942
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(127)	(136)	(281)	(290)
Recoveries		28	30	53	58
Provision for credit losses		134	128	263	235
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		990	945	990	945
Consumer: | Other consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		989	959	994	890
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(146)	(141)	(300)	(306)
Recoveries		31	28	61	56
Provision for credit losses		177	112	296	318
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		1,051	958	1,051	958
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		415	388	431	385
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(70)	(74)	(144)	(151)
Recoveries		12	9	23	18
Provision for credit losses		58	84	105	155
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	0
Ending balance		415	407	415	407
ALLL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		4,870	4,803	4,857	4,798
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(506)	(535)	(1,063)	(1,135)
Recoveries		110	93	213	203
Provision for credit losses		430	446	896	942
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	(5)	1	(4)	0
Ending balance		4,899	4,808	4,899	4,808
RUFC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		296	297	304	295
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		0	0	0	0
Recoveries		0	0	0	0
Provision for credit losses		58	5	50	9
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	0	0	0	(2)
Ending balance		354	302	354	302
ACL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,166	5,100	5,161	5,093
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff		(506)	(535)	(1,063)	(1,135)
Recoveries		110	93	213	203
Provision for credit losses		488	451	946	951
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other	[1]	(5)	1	(4)	(2)
Ending balance		$ 5,253	$ 5,110	$ 5,253	$ 5,110

[1] Includes the amounts for the ALLL for PCD acquisitions and other activity.